Technical Field
The present invention relates to the field of cleaning aqueous fluid streams, and more specifically, provides a processing unit for aqueous fluid streams which improves the flocculation and separation of contaminants by increasing the amount and size of the floc, which provides for much improved separation and removal of contaminants from the aqueous fluid stream.
Background
Electro-(coagulation precipitation or flocculation) entered into commercial application with Cottrell's smoke stack dust precipitator in the late 1800's. One of the best representations of the art as applied to fluids is the Liggett patent, U.S. Pat. No. 4,293,400. All others are some variation of the basic concept. Some of the best documentation of the results of Electroflocculation was presented in U.S. Pat. No. 4,872,959 titled “Electrolytic Treatment of Liquids” as presented by Robert J. Herbst and Russell R. Renk with their patent of the “tube within a tube” configuration. However, the time consuming maintenance required by this configuration, cost of special parts fabrication, difficulty locating close tolerance tubing and maintaining proper clearance between the inner and outer tubes necessitated that a better solution be found. In U.S. Pat. Nos. 4,293,400, 4,378,276 and 4,872,959 there are described devices for applying an electric field to a liquid flowing through the devices. These devices employ the tube within a tube configuration. In U.S. Pat. No. 5,043,050, which is by Robert J. Herbst, all of the many, noted problems of cost, material acquisition and difficulties of maintenance of the tube within a tube device are quite well covered.
There have been many methods put forward for the removal of contaminants from aqueous fluid streams. There exist many forms and shapes of electrocoagulators. Most electrocoagulation (Electroflocculation) units are quite difficult to maintain and clean out. This must be accomplished on a regular basis if the units are to perform correctly. As a solution to this, some have advocated using chemicals while others have added a fluidized bed of conductive particles to aid in eliminating this problem. This usually just introduces a new problem.
U.S. Pat. Nos. 4,053,378, 4,094,755 and 4,329,111 describe using flat plates and fluidized beds. The flat plate device patents discuss the need for caution due to maintenance problems encountered caused by buildup of solids from the fluid stream on the carbon granules used in the fluidized bed. All of these devices are single technology treatment units.